In recent years, video coding (video compression) has become one of the widely explored topics in the field of visual communications. With the rapid development of video and multimedia technologies, digital video applications are becoming more important in people's lives. The demand for digital video communication, such as Internet Protocol Television (IPTV), MobileTV, video gaming, video surveillance, videoconferencing, mobile video broadcasting and videophone, and so forth, has increased considerably thanks to the success of advanced video coding techniques, such as H.264, MPEG-4, etc.
The state-of-the-art coding schemes have greatly improved the coding efficiency and subjective visual quality. However, due to the scarcity of channel resources and the restriction of transmission rates, further improving H.264 coding efficiency and encoding video sequences at very low bit-rates with good quality remain major challenges. Thus, the pursuit of performance improvement continues. Many coding schemes consider the property of the human visual systems and try to introduce the concept of region-of-interest (ROI) to improve the coding efficiency and error resiliency of the existing standards.